We have established a Pediatric Neuromuscular Clinical Research Network (PNCR) to evaluate patients at three sites: New York, Boston and Philadelphia. Data management (including fully web-based data repository) and statistical analyses will be carried out at the University of Rochester by the "Muscle Study Group Data Center", which is a group experienced in clinical trials of neuromuscular disease. We will characterize the patient population using selected outcome measures, standardized among sites. The clinical trial planning phase will focus on developing the necessary infrastructure between sites, critically evaluating candidate outcome measures, obtaining pilot data using those outcome measures, and establishing their reliability. In parallel to the proposed study we will work closely with the preclinical units of the Columbia University SMA research center to identify and prioritize candidate drugs for future clinical trials. Finally, based on the observational data from the proposed study, and discussions among the network's clinical experts we will develop efficient phase I/II clinical trial designs to test candidate drugs. This clinical research is timely and relevant, because laboratory research has identified candidate drugs for SMA. There is currently no effective treatment for this devastating disease. All activities of the Network will conform to established regulations that govern clinical research and patient privacy (HIPAA).